Police constable George Gutteridge was found dead in September 1927 on a byway near Howe Green, dressed in his full police regalia, shot four times in the face while apparently in the process of writing up a miscreant motorist.

Frederick Browne (top) and Pat Kennedy.

Two of the shots had been through each of Gutteridge’s eyes, conceivably in deference to the ancient superstition that dead men’s eyes preserve the last image they beheld in life. If that was the reasoning, Frederick Browne, the triggerman, was living in the wrong century.

The “Gutteridge murder” investigation — a national sensation from the time the constable’s mutilated body was discovered — took several months to hone in on suspects Browne and Kennedy, known car thieves with some history of violence. But the real break in the case was, well, a case: a cartridge case from a .455 Webley recovered at the crime scene. It would be the most eloquent witness against Browne and Kennedy.

The now-familiar science of forensic ballistics was, though notquite brand new, still an occult art in Anglo courts of law. Just days before Gutteridge’s murder, Sacco and Vanzetti had been executed in the United States based in part on ballistics studies. That gun-barrel research had been continued in the post-conviction appeals and clemency investigation, and provided one of the clinching pieces of evidence against the anarchists, but it was also ferociously contested.

In Great Britain, it was the Gutteridge case that put this field on the map for the general public — courtesy of professional gunsmith and ballistics investigator Robert Churchill.

Churchill used microscope analysis of the recovered casing to match the bullet not only to a .455 Webley, but to the .455 Webley recovered from Browne’s car: to that gun, and no other.

Post-Browne and Kennedy, murderers given to gunplay became very well advised to dispose of weapons once they’d been used: this case served notice that individual handguns left a sort of fingerprint on the rounds they discharged, and could thereby incriminate their owners months or years after the fact.

This conclusion was not universally embraced, perhaps owing in part to the role of ballistics in the controversial Sacco and Vanzetti affair: according to Basil Thomson, George Bernard Shaw wrote to Browne’s family during the trial to express his skepticism, complaining of the crown’s “manufactured evidence.” In 1932, the renowned barrister Patrick Hastings successfully repelled Robert Churchill’s firearms evidence at the high-profile murder trial of Elvira Barney.

But the reason Churchill was on the stand on that occasion was because his damning testimony in 1928, explaining where a small fault in the Webley’s breech block had scarred the bullet as it launched, not only sufficed to hang Browne and Kennedy* — “hanged by a microscope”, in the words of The Sunday Dispatch — but also launched a star career for Churchill personally, and made the bones of firearm ballistics for modern criminal trials.

* More precisely, the forensic testimony hanged Browne — who stuck with a flat denial, which the ballistics associated with his own gun refuted. Kennedy lacked the wit to shut his mouth and in the course of trying to spin his story to throw all the blame onto Browne also just by the by confessed to his own involvement.